A heat pump, such as, for instance, a residential or commercial refrigerator, freezer, or air conditioner, may use a vapor compression circuit to transport heat from a low temperature reservoir (e.g., outdoor air) to a high temperature reservoir (e.g., hydronic heating water). The vapor compression circuit may be designed and/or controlled in such a way as to transport the heat with the highest possible efficiency. The efficiency of the vapor compression circuit can be characterized by the ratio of the transported heat to the mechanical and/or electrical energy consumption (e.g., compressor electric power consumption) of the circuit, and this ratio can be denoted as the coefficient of performance for the heat pump.
The vapor compression circuit of a typical heat pump may include a liquid refrigerant receiver, which can be an accumulation vessel that holds (e.g., stores) excess liquid refrigerant present in the circuit. Holding the excess liquid refrigerant in the receiver can reduce the vapor compression circuit's sensitivity to the charge of the refrigerant (e.g., to changes in the charge of the refrigerant during operation of the circuit). Further, utilization of a liquid refrigerant receiver can simplify operation of the vapor compression circuit, and therefore simplify operation of the heat pump.
Compressors can be a vital part of the vapor compression circuit. Compressor failure can cause the vapor compression circuit to fail and/or cause a refrigeration system to fail. In some cases a compressor failure can cause high cost to fix quickly or can cause a high cost due to damage to products within the refrigeration system.